How do I accomplish this desired action? -->
R-click a tab, Select "Move Tab to (L/R)" , but then add "Activate" or "Take Focus"?
** I'd prefer to modify this existing behaviour vs. creating some new button/hotkey?
I got as far as going into: Customize > Commands > Add New User Commands >
Commands > Go
Argument > TABMOVE/O
I've also read 6+ threads describing almost the same request -
I liked this one since it requires 1 click + keypress, but still it lacks the "Activate Tab" functionality.
I'd like to add an even better (lazy man's) possibility here --
Preferences > File Displays > Mouse > "Middle double-click on file display background"
-- further modified by "Single middle click to trigger middle double-click events on background and files'
(so that only a SINGLE middle click on display bkgd is required)
to produce my desired action of "Move Tab to (L/R) then Activate It"
** I have plain old "Double-click on file display background" = Go UP BACK
Man, I'm playing with these modifiers like Go NEWTAB, etc,
but I just can't quite make everything work yet -- can't find these "Internal" ? commands
still .... it sounds goofy but I look forward every morning to firing up a computer b/c of dOpus 
Thx Leo! 
Prefs > File Displays > Mouse > "Middle double-click ... etc" > Command:
Command: Go TABMOVE=active Set SOURCE=Toggle
I didn't know if that Command: box was gonna take the whole string, but it obviously does.
So that solves my 2nd & Higher Priority request, and I'm grateful b/c that one takes least effort!
But out of desire to learn more, can the initial request be accomplished?
i.e. - can the "click on the tab's" behavior be modified? or is that too deep in the app code?
(not accessible to the end-user)
The tab right-click menu can't be edited but it's something we're considering.
(Edit: It can be edited these days.)
Thx - it's useful to understand that. (Oh - & mark SOLVED if y'all do that? I don't recall)
(Oh -- I see I do that 
)